So Far, Drug Testing Has Revealed Only a Few Positives

On July 27, the International Olympic Committee began its biggest effort to catch athletes who are using performance-enhancing substances.

Its results so far raise two questions: Where are all the positive tests that experts expected? And are these Games cleaner than ever or are the athletes simply better at foiling the testers?

High-profile athletes like Michael Phelps have been extensively tested, each time with both blood and urine tests. He had a test Aug. 2, when the United States swim team was in Singapore. The team arrived at the Olympic Village in Beijing on Aug. 4, and Phelps was tested again.

"We had been here an hour in the village when they went here and got him," said Dr. Scott A. Rodeo, a team physician for USA Swimming who is an orthopedist at Hospital for Special Surgery in New York. Since then, Phelps has been tested seven times, Rodeo said, including twice on Aug. 11.